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What is polonium?

Read more on the history of the rare and highly radioactive substance found in Arafat's final personal belongings.

06 Nov 2013 GMT+3

Polonium is a rare and highly radioactive element. It is found naturally in the atmosphere and in the earth’s crust, though in miniscule quantities. World-renowned scientist and Nobel laureate Marie Curie discovered the element in the late 19th century and named it after her native country Poland (Polonia in Latin).

Polonium has dozens of isotopes. One of the most common is polonium-210, which emits highly radioactive particles, known as alpha particles. This was the isotope found on Yasser Arafat’s personal effects during Al Jazeera’s initial investigation into What Killed Arafat?

Because of its radioactivity, polonium has been used as a trigger for nuclear weapons, and as a power source for satellites and other spacecraft. The Russian space programme used it to heat rovers that landed on the Moon in the 1970s.

Polonium is harmless when it is outside the body, but after ingestion it becomes one of the deadliest substances know. An amount equivalent to the size of a particle of dust is lethal.

Ingesting just 50 nanogrammes, or inhaling 10 nanogrammes, of the substance can cause death. This means one gramme of polonium-210 could theoretically poison and kill about 10 million people.

What are the symptoms of polonium poisoning?

Because there have been so few recorded cases, there is not much scientific literature on the subject.

After ingestion, polonium quickly gets into the bloodstream where it bombards blood cells with millions of radioactive alpha particles, which damages vital organs - first the liver and kidneys, causing jaundice and then the intestines causing toxic shock syndrome. Finally it attacks the heart.

How is polonium produced?

Polonium occurs naturally in uranium ores, but at extremely small concentrations; as low as 100 microgrammes per tonne of ore.

Rather than laboriously extracting it from uranium, modern-day manufacturers create polonium in nuclear reactors by bombarding the element bismuth with neutrons. Most of the world’s polonium supply is produced in Russia.

Natural levels of polonium that accumulate on surfaces barely register, and the element disappears quickly. Polonium-210 has a half-life of 138 days, meaning that half of the substance decays roughly every four-and-a-half months.